Can anyone suggest what might be wrong?
I have just changed the clutch and now I am struggling to select gears even when the engine isn't running.
I don't think it's linkage related because it seems to be difficult to select gears just pulling directly on the arms that move the forks too. I don't think I've done anything that should have an effect on the inside of the gearbox, I've removed and refitted the drive shafts and changed the fluid.
Also can anyone confirm my thinking that the clutch and concentric slave cylinder shouldn't be a factor, since the problem exists when the engine isn't running?
Edit: Strangely, after leaving it overnight, gears are selecting perfectly again and I have absolutely no idea why. I didn't change anything 😕
I suppose that should be good news but without knowing what the problem was, I'm not very satisfied. Thank you to everyone for your help.
Yes, I did. I didn't actually fully remove the transmission to avoid removing the front subframe. There was just enough space to separate the gearbox and engine and slot the new clutch assembly in.
I think it sounds like a single selector fork too, but I can't think how I could've damaged it, since I don't think I have done anything that should affect the internals of the gearbox 😢
Okay, I am going to guess that when you spit the bell housing you moved the transmission and not the engine. I am also going to bet that you didn't disconnect the shifter linkage first. I am not saying it is likely but as you moved the transmission it is possible that the link pulled on a selector fork (is it cable linkage?)
So this is what I would do to try to narrow the fault down. Jack up one drive wheel and put it in gear. With the engine off the wheel shouldn't turn. Now leaving it in gear and push the clutch in, the wheel should now turn. If that is normal it is most likely not the clutch.
Now disconnect the shift linkage at the transmission. This should free the shifter. So make sure that it moves freely.
Lastly with the shift linkage disconnected and the clutch pushed in see if you can move the selector forks by hand.
That should narrow it down for you
Even a selector fork that is a little bent can really screw with shifting, it can sometimes make the transmission be in two gears at the same time.
I could also see this fault happening with a damaged clutch basket/fingers or a bad slave cylinder. Did you leave the slave cylinder attached to the hydraulics? Some clutch hydraulic systems are unbleedable. If you did some that could have gotten air in the system. Does the clutch feel normal?
I left it overnight, and now the gear change is back to normal and I have no idea why 😭
That's a really great way to find the problem, and if it starts happening again I will follow exactly that process 🙏
It may not matter now, but for the sake of completing the picture:
I did move the gearbox but I also disconnected the linkage beforehand, carefully and gently too.
It's a bleedable (concentric) slave cylinder which I replaced with the clutch as it has an integrated release bearing. I've now been able to test the clutch properly and it feels excellent 👌
If the problem comes back and I am able to find the cause, I will make sure to report back!
That is weird. It seems like you did everything right. I can't really see why this would happen. With it going away like that it seems like it must be something to do with the clutch... Maybe it didn't seat properly and you fixed it when you were trying to diagnose it. Or maybe you had some weird air pocket in the clutch hydraulics that needed time to rise to the top.... I don't know
I would keep an eye on your clutch hydraulic fluid for a bit just to be safe. Otherwise just be happy it went away. I know I hate not knowing what was wrong even when it gets fixed.
Or as I think maybe you had a selector fork get stuck and it released overnight....